(a) Field
The present invention generally relates to a cross carrier scheduling method and apparatus.
(b) Description of the Related Art
Recently, a carrier aggregation is developed as a scheme for extending service bandwidths. By using the carrier aggregation, a terminal can simultaneously receive a service from a primary cell and a plurality of secondary cells.
A cross carrier scheduling is an example of the carrier aggregation, and is a scheme for transmitting data transmission information of other carrier through a physical downlink control channel (PDCCH) of one carrier. The PDCCH of one carrier can transfer resource allocation information of a physical downlink shared channel (PDSCH) and a physical uplink shared channel (PUSCH) transmitted or received through own carrier, and resource allocation information of the PDSCH and the PUSCH transmitted or received through other carrier, by using a carrier indicator field (CIF). If the cross carrier scheduling is used when the plurality of secondary cells are set, the terminal can perform PDCCH monitoring for only a carrier requiring the PDCCH monitoring, thereby reducing consumption of a battery.
Scheduling configuration information of the secondary cell set to the terminal may be changed in the cross carrier scheduling. In this case, a base station transmits to the terminal a radio resource control (RRC) reconfiguration request message including cross carrier scheduling configuration information. The terminal changes the cross carrier scheduling configuration information of the secondary cell indicated by the RRC reconfiguration request message, and transmits a RRC reconfiguration complete message to the base station. When changing the cross carrier scheduling configuration information of the secondary cell, the terminal starts the PDCCH monitoring for reconfigured scheduling cell of the secondary cell according to the changed cross carrier scheduling configuration information.
In the case that the base station applies the PDCCH transmission in the reconfigured scheduling cell at a time when receiving the RRC reconfiguration complete message, a time when the base station transmits the PDCCH to the reconfigured scheduling cell is inconsistent with a time when the terminal monitors the PDCCH of the reconfigured scheduling cell. Alternatively, in the case that the base station applies the PDCCH transmission in the reconfigured scheduling cell at a time when transmitting the RRC reconfiguration request message, a time when the base station transmits the PDCCH to the reconfigured scheduling cell is inconsistent with a time when the terminal monitors the PDCCH of the reconfigured scheduling cell. Accordingly, during the inconsistent period, data transmission or reception to the secondary cell can be discontinued, and unnecessary signaling overhead can occur.